Utilization of naphthenic acids



Patented June 14, 1938 UNITED STATES PATENT OFFICE No Drawing. Original application February 25,

1932, Serial No. 595,237. Divided and this application June 3, 1935, Serial No. 24,716

1 Claim.

My present invention relates to naphthenic acids, and more particularly to the utilization of such acids; the present application being a division of my application Serial No. 595,237, filed 5 February 25, 1932, which has issued as U. S. P. 2,003,640.

A mixture of acids, known as naphthenic or petroleum acids, occurs in mineral oils primarily obtained at the present time from certain sources.

The latter comprise Russia, Roumania and the United States; Texas and California being the primary producing States of mineral oils. The usual practice in refining such oils is to distill the oil over caustic soda, the sodium salts of the naphthenic acids remaining as a thick, black sludge containing a large percentage of petroleum oil. Impure naphthenic acids are customarily recovered from the sludge by treating the latter with a mineral acid, sulfuric acid often being chosen as such an acid. These naphthenic acids are of great potential value. However, the widest commercial exploitation of the acids has been inhibited by the technological complexities, as well as high operating cost, encountered in completely separating the acids from the oil.

The prior art contains many illustrations of uneconomical methods of recovering naphthenic acids from the mineral oil sludge. In all of these methods it is clearly demonstrated that those skilled in the prior art have failed to realize, or

appreciate, the true physical nature of the sludge. For example, solvent extraction methods, washing processes and like procedures have been resorted to in a vain attempt to completely free the naphthenic acids from the mineral oil.

An important object of the present invention is to provide methods of, utilizing naphthenic acids recovered from mineral oil sludges by a deemulsifying process, which methods result in the production of highly valuable compounds adapted to be employed in such widely diverse uses as pigmented protective paints; plasticizers; lacquers, shatter-proof glass; polishing waxes; oil flotation promoters; rubber accelerators; and many other uses.

The novel features which I believe to be characteristic of my invention are set forth in particularity in the appended claims; the invention itself however, will best be understood by the following description wherein there is indicated several methods whereby my invention may be carried into eifect.

Before describing in detail the procedure to be followed in utilizing the naphthenic acids of the present invention, the general aspects of the recovery process herein disclosed will be outlined. The present method of separating the oil and alkaline naphthenate salts of the mineral oil sludge depends for its success upon the breaking up of the emulsoid state existing between the oil 5 and the salts. Hence, it is first essential to considerably minimize the stability of the bond (Whatever its nature) existing between the oil and the naphthenate salts.

Accordingly, the sludge is completely dispersed 10 in water, and the resulting aqueous mixture is maintained at a temperature sufficiently high to prevent gel-formation throughout the subsequent treatment. To the aqueous mixture is added a thinner. The latter has a boiling point above 15 the temperature of the aqueous sludge mixture; is of low viscosity; and acts as a solvent for the oil. The thinned mixture is thoroughly agitated in order to secure good contact between the oil and the thinner. 20

Suitable thinners which can be utilized are benzol; toluol; xylol; naphtha; kerosene; ethyl ether; carbon tetrachloride; amyl alcohol; amyl chloride; butyl acetate and the like.

An' agent is now added that will break the emulsion formed, and thus effect a complete separation of the oil and thinner from the aqueous solution of the naphthenate salts. Suitable deemulsifying agents which can be employed comprise the Water-soluble organic materials of rela- 30 tively low viscosity, and the water-soluble salts of sodium, potassium and ammonia.

Illustrations of such de-emulsifying agents are methyl, ethyl, and propyl alcohol; acetone; methyl and ethyl acetate; butyl amine; sodium, 35 potassium and ammonium chlorides; sulfates; nitrates; iodides; oxychlorides; etc. or their mixtures. The layer of thinner and oil is then drawn off, and the remaining aqueous layer of alkaline naphthenate salts is treated with a min- 40 eral acid. The naphthenic acids are thus recovered.

Local conditions afiecting the composition of the sludge, convenience in handling the latter, and purity of naphthenic acids desired will, of 45 course, determine variations in the aforedescribed method. Thus, while the group of naphthenic acids referred to herein are characterized by boiling points ranging between C. to 350 0., the present process may be applied to a 50 sludge containing but one, or any predetermined number, of the group. Hence, the expression naphthenic acid or naphthenate used hereinafter is to be understood as meaning a member of the above group. 55

Having obtained naphthenic acid as a substantially pure product according to the aforementioned recovery process, the acid may be employed in widely diverse uses. Thus, a pigmented, elastic protective paint may be readily made by neutralizing naphthenic acid, as made above, with sodium hydroxide, and reacting the resulting sodium napthenate with an aluminum salt, such as aluminum sulfate. The pigment is introduced into the reaction mixture. Hence, the precipitate of aluminum naphthenate carries down with it the pigment in fine admixture therewith. Introduction of the pigment prior to precipitation assures the production of a successful pigmented paint, since it is difficult to thoroughly mix the pigment with the naphthenate at a later point. The aluminum naphthenate and pigment precipitate is dried, and then mixed with turpentine until thoroughly dispersed. The resulting paint is an excellent protective paint for wood or steel, and is sufficiently elastic to resist wide variations in temperatures.

Naphthenic acid secured by the above recov ery process is adapted for use in the manufacture of butyl naphthenate which is to be employed as a plasticizer. The acid is converted to the butyl ester by refluxing the acid with butyl alcohol while passing dry hydrogen chloride gas through the reaction mixture. The resulting reaction product is distilled to secure the butyl naphthenate. The latter serves as a desirable plasticizer for nitrocellulose and cellulose acetate paints and lacquers, since it permits the use of cheap solvents such as naphtha, benzol and the like. It is to be understood that instead of butyl alcohol, there may be used alcohols such as propyl, methyl, ethyl, or benzyl alcohol, to produce the respective naphthenic ester.

Another use to which the naphthenic acid can be put is in the production of cellulose napthemate. The elasticity of the latter is five to ten times as great as cellulose nitrate and cellulose acetate, and therefore this compound is readily adapted for use in shatter-proof glass of the well known type wherein alternate layers of glass and cellulose compound are processed to form a sheet of glass. Further, since the cellulose naphthenate is readily soluble in cheap solvents, such as benzol, it can be used in elastic lacquers. Briefly, the cellulose naphthenate is made by reacting naphthenic acid with phosphorus pentachloride to yield naphthenic acid chloride. The latter is reacted with pure cellulose, in the presence of pyridine or aluminum chloride, to give the cellulose naphthenate. Of course, the aforedescribed naphthenate esters are readily usable as plasticizers in a cellulose naphthenate paint, since they are both soluble in cheap solvents, usch as benzol.

Liquid, or solid, polishing waxes can be made from the naphthenic acid, procured as described herein, by reacting a polyhydric alcohol, such as glycol or glycerine, with the acid. The reaction is carried out in the presence of a condensation agent, such as hydrogen chloride gas or SOClz, and the resulting ester is naphthenic glycol, or glyceride, as the case may be. The naphthenic ester is dispersed in soapy water to produce a liquid polish; or, to produce a solid polish, it may be mixed with a wax, such as carnauba wax.

Another important use to which the recovered naphthenic acid can be put is in the synthesis of the alcohols of the naphthenic acids. For example, by reducing one, or more, of the acids of the naphthenic group of acids in a hydrogen atmosphere, at a temperature of about 200 C., and a pressure of about pounds per square inch, and in the presence of a catalyst (as finely divided nickel or copper), the naphthenyl alcohols may be produced. Any, or all, of the naphthenyl alcohols can be converted into naphthenyl xanthates by treatment of naphthenyl alcohol with CS2 and sodium hydroxide. The naphenyl xanthates are especially useful as promoters in oil flotation processes. They are additionally well adapted to serve as accelerators in rubber vulcanizing and compounding. Other naphthenic acid derivatives that are useful, for example as plasticizers in cellulose derivative plastics, are the naphthenyl phosphates. The latter can be produced by treating the naphthenyl alcohols, obtained as above, with POCls.

It will now be appreciated that the present method of recovering the naphthenic acid content of mineral oil sludge lends itself readily to the subsequent production of many naphthenic derivatives which have varied uses. Further, the economy of the recovery process permits the production of the said derivatives, whereas the methods employed in the prior art to recover the naphthenic acids have proven to be so uneconomical that the extensive use of the naphthenic acids was discouraged.

While I have indicated and described several steps for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular steps shown and described, but that many modifications may be made without departing from the scope of my invention as set forth in the appended claim.

What I claim is:

A method of producing a naphthenyl alcohol which consists in reducing a naphthenic acid in a hydrogen atmosphere at a temperature of about 200 degrees C., and under a pressure of about 150 pounds per square inch in the presence of a hydrogenation catalyst.

JULIUS A. WUN SCH. 

